html{
    font-size: 16px;
}
body{
    margin: 0;
    width: 100vw;
    height: 100vh;
}
ul{
    margin: 0;
    padding: 0;
    list-style: none;
}
a:hover{
    text-decoration: none;
}

/*有关页面头部 布局的样式*/
.header-wrapper{
    /*固定到页面顶部*/
    position: fixed;
    top: 0;
    z-index: 900;
    width: 100vw;

    /*弹性布局*/
    display: flex;
    justify-content: space-between;
    align-items: center;

    padding: 10px;
    /*background-color: yellow;*/
}